1. Field of the Invention
The invention relates to a method and apparatus for recovering metallic lead from "battery mud" and more particularly to reducing the finely divided lead compounds directly in a reducing flame.
2. Prior Art
A significant part of the lead used for commercial purposes is reclaimed from worn out electrical storage batteries. During the reclaiming operation, the lead compounds which form the active material on the plates are recovered as a thick paste commonly called battery mud. Conventionally, this paste is dried, agglomerated and smelted in a reverberatory furnace where the lead compounds are reduced to lead. It is usually desirable to remove most of the sulfates by reaction with ammonium carbonate to avoid the production of SO.sub.2 in the furnace gases. The necessity of agglomerating the battery mud adds to the time and cost required to extract metallic lead from the battery mud.
It has been suggested in U.S. Pat. No. 3,862,834 that finely divided iron ores can be reduced by forming the dust into a cloud, transporting the cloud in reducing gas, reacting the cloud with the gas for enriching the dust, and then introducing the transported cloud into the plasma stream of a plasma burner directed at the bath of a melting furnace. It has also been suggested in U.S. Pat. No. 3,459,415 that finely granulated copper-bearing sulfidic materials can be introduced into a converter where they are subsequently melted and reduced by injecting them through a pipe coaxially mounted inside a second larger pipe carrying a pressurized oxidizing gas. The stated purpose in this instance of introducing the oxidizing gas with the ore concentrates is to promote a separation of the materials in the converter into distinct layers.
U.S. Pat. No. 3,463,472 discloses apparatus for continuous direct smelting of ores in which a continuous flow of molten material is promoted between various zones within a furnace by jets of oxygen. In one embodiment, prereduced, finely divided ores mixed with powdered coal are introduced into the furnace through a water-cooled feeder-burner. The feeder-burner comprises a central pipe through which the fines are fed at sufficient velocity to penetrate the slag layer and two concentric rings of pipes surrounding the central pipe. Oil or propane and air or oxygen are directed from the concentric rings of pipes parallel to the stream of fines to produce a flame which restores the heat lost from the fines during transport from the prereducer to the furnace and to aid in circulation of the molten material in the furnace.